MCP surface for tkn CLI

[vdemeester]

Summary

Expose tkn as an MCP (Model Context Protocol) server, enabling direct integration with AI agents like Claude Code without requiring shell execution. This could consolidate the standalone tekton mcp-server into the tkn binary itself.

Proposal

• Expose tkn operations as MCP tools via JSON-RPC
• Support tkn mcp serve or similar to start MCP server mode
• Maintain CLI, kubectl plugin, and MCP surfaces from a single binary
• Support environment variable credential injection for headless execution

Acceptance Criteria

• tkn can serve as an MCP server exposing Tekton operations as tools
• MCP tools cover core operations (list, describe, create, start, logs)
• Single binary serves CLI, kubectl plugin, and MCP interfaces
• Migration path documented for standalone tekton mcp-server users

Context

Part of #2849 — making tkn agent-friendly.

Note: A standalone tekton mcp-server already exists. This epic would evaluate consolidating that into tkn itself to reduce deployment complexity. Deprecation timeline would be coordinated with the Tekton community.

/kind feature